Java DataOutputStream writeDouble()用法及代碼示例

DataOutputStream類writeDouble()方法

• writeDouble() 方法可在java.io包。
• writeDouble() 方法用於將給定的雙精度值寫入基本的 DataOutputStream。
• writeDouble() 方法是一個非靜態方法，它隻能通過類對象訪問，如果我們嘗試使用類名訪問方法，那麽我們將得到一個錯誤。
• writeDouble() 方法可能在寫入 double 時拋出異常。
  IOException:在獲取任何輸入/輸出錯誤時可能會拋出此異常。

用法:

    public final void writeDouble(double val);

參數：

• double val– 表示要寫入數據輸出流的雙精度值。

返回值：

該方法的返回類型是void，它什麽都不返回。

例：

// Java program to demonstrate the example 
// of void writeDouble(double val) method 
// of DataOutputStream

import java.io.*;

public class WriteDoubleOfDOS {
 public static void main(String[] args) throws Exception {
  InputStream is_stm = null;
  DataInputStream dis_stm = null;
  FileOutputStream fos_stm = null;
  DataOutputStream dos_stm = null;

  double[] d = {
   10.0,
   20.0,
   30.0,
   40.0,
   50.0
  };

  try {
   // Instantiate FileInputStream, 
   // DataInputStream, FileOutputStream
   // and DataOutputStream 
   fos_stm = new FileOutputStream("C:\\Users\\Preeti Jain\\Desktop\\programs\\includehelp.txt");
   dos_stm = new DataOutputStream(fos_stm);
   is_stm = new FileInputStream("C:\\Users\\Preeti Jain\\Desktop\\programs\\includehelp.txt");
   dis_stm = new DataInputStream(is_stm);

   for (double val:d) {
    // By using writeDouble() method isto
    // write double value to the
    // DataOutputStream dos_stm
    dos_stm.writeDouble(val);
   }


   // By using flush() method isto
   // flush the bytes to the basic 
   // output stream         
   dos_stm.flush();

   // Loop To Read Available Data till end
   while (dis_stm.available() > 0) {
    // By using readDouble() method isto read 
    // double from dis_stm
    double val = dis_stm.readDouble();
    System.out.println("dos_stm.writeDouble(val):" + val);
   }
  } catch (Exception ex) {
   System.out.println(ex.toString());
  } finally {
   // To free system resources linked
   // with these streams
   if (is_stm != null)
    is_stm.close();

   if (dis_stm != null)
    dis_stm.close();

   if (dos_stm != null)
    dos_stm.close();

   if (fos_stm != null)
    fos_stm.close();
  }
 }
}

輸出

dos_stm.writeDouble(val):10.0
dos_stm.writeDouble(val):20.0
dos_stm.writeDouble(val):30.0
dos_stm.writeDouble(val):40.0
dos_stm.writeDouble(val):50.0